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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbc6be5d6642f621e07daf3b3d0d35b345fac2c53abb8d9f8d63e3a191e127ad' 
  AND token = 'ukD3ItcRxlvuQaWDvi4uN9iVtt5VvSuPK5t5ACfU3oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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