SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a1b2a7230bc6af6431281505f7397d0b5fa104334ea5060da85a590c5c1984e' 
  AND token = '5yrpB+yDe6yobQ5HF+bagGaj4UUSgk26RHFsbr74DcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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