SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bed375ef1b1cca0d43df40b069fd7142d8625a0b2536b2fdedab5c65d66e7568' 
  AND token = 'y/0yCjuRZJjAz+JKElPpYC+c9bHfeFKUuTGmY59Up1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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