SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68c71aa4221e25d981c0aca9c680b584294725697812c1aa3fd3e0b0b3991d6a' 
  AND token = 'h11cadOgFsAIHGPjtUknID5pQKgRYG0jwm4JdnIZEEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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