SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398a4c37cf3509bed9761c7a7adbf2e45b9d1d71b0638ce451e58b77d94ce4c6' 
  AND token = 'y4g8/EHCEJd5hjmXwihIG8aZCXXQfKik0LPKz68jKDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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