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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da749a7e98966c6646ce85478ea6e86b79037f3954f3b82c4d4cd8e180d40f58' 
  AND token = 'RjF8wncHMkutQtKDN+wWJaJ8+nWMn88rSLUFRcI2vEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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