SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f6eb40fca1f28716648074e024506b1d178f969cf22fe1175c61ec1622c66e9' 
  AND token = '727OzVjDMRytD6b1jcV0bcpfZxvYXnncdzCxHZQ0VmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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