SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0ac5d96a9b73b3cd20e15763c702822b72128b99791cd0772ea76e29287171c' 
  AND token = 'n2kYqUsYNTZAov2DkDuV+Eny+Ghzq8QqPj9vnOw3+vs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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