SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a1fd96b51af2786ae70f119ada55354a643991cf7050ee8ea81f650b387d5ec' 
  AND token = 'xlpmXSaBRR/cZi2tdgw+68lUjFJl7BjZpOK7mdXTxGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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