SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '259c9595ce72e99c7f43a98392a12725f6643acdeba4d279c812b50401de35ef' 
  AND token = 'I91gjlqde7S0oqzGzpn1YD1JhGZwlO0sfiG4Ss579FU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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