SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db128a52d432bcd68a39146a1c94d0153dab5b85961bfb5d8a57a18916cd4452' 
  AND token = 'BbtQdUkxAOd8G93P3336f+sHWS88qPPygvyDKiuJ9gE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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