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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a8ebfc0dafc96858ab0fc36ab3481fdaef8e7a6c31457768d7cb91e223e2c36' 
  AND token = 'IGn1XNvcS9Jcx3gt5Rp7SCFi+FEaw//QqyE0hm+b3Y4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}