SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74c00c36f3c94523781e42481be804b4a501975e738e917cdb0ece9df36674d1' 
  AND token = 'S6GKY3lBvD0rhjQ+CT6zkY/PdlKIryEpGtGPng8ZD08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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