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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '775dba0c9dcbc4c8021912597d08b927f4fac6d68922d6a93e86445c21ed11cb' 
  AND token = '4ebC4kUKbOb92PoPC0nfBCNOWYFdH8RL3uuVxTSQxDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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