SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd42cc960b351b15486285c8267208c6d941a91ec707f452c0324484f5969f921' 
  AND token = 'Q/vNDw4PqAN9LhzGn92CsDVFWzSbABZ/8B28bJuqsig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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