SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da0cb2a7cb4632d9a6d81f920c9354aa0a556897ea140b4c02b7d47561244de9' 
  AND token = 'GVQa/DkMuV7//gZfv904DWXwJhatR2uuLYmyBzWQeYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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