SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '599a7295fe2cd2e0f31770f2146d519f4f740e92d025558b7d1d811f2fe7943f' 
  AND token = 'K9dUds/4mAvon3EqZTdmBHg6LS1KMaEwDq7hw3WZjeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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