SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '108a0b63b755c79649040c293464329802b20615c6018696f2ac918883880fee' 
  AND token = 'jWAR6IIta82wHhYYafWyG2Jz3LTqD4FO+bgSXqaWLUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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