SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3dcb6b4d9ac21fc868805902fd2823d193525b0c62c5a5638d1b1a15a44138b' 
  AND token = 'mzIDiwtxDiwmE56gBwhuBjBtN4C/6hBXtQpqTWZzL4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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