SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bc16a73148292275c6a9f8f2546481a17aba6701d4a0236a4be9d03fbcbb406' 
  AND token = 'TSz7+Tuw3KGVVIu8iNINvqHb7ZsaWjA/dMBWcq52tCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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