SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2781b63b232df929fe547895be395448eb2fafe815cc5536413dbf4ab56e7c2' 
  AND token = 'SEksQ1szFXq83Wb4aCkSFT95zUFv+cz5L47s3kmDAwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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