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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42c7be0c009d4d72163f10c246b9a9b0b03e56dc8ab7ebfbb78a3cfc06970a4' 
  AND token = 'IMz1ECjgyO/whMuzS1QLyH1M4l8jr5jJ9zfXTWug/UQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}