SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d3a64de6a121830d619f11196eee17d245b806ceea111e62bec0fea64a64e38' 
  AND token = '+jLZG+ZqUj1m179yIbwKsfkSN1eIXZve2rjUHF4UQhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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