SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e6e876a559634b1a99e1fc3376256332926b1d20bffd994781dd07e5f62d351' 
  AND token = 'XNkQdJCxCsShuGakj6zCWvC+vOVPQU/Duqp32tjyX6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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