SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef76898565453849cc21b59735f46eafaefce86a058d694056b973beea4bae05' 
  AND token = 'H3RQZXmGfaV9gaaJml5+ap/Q8VAFa5jPmxjc7ZFEKgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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