SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e0f4474168429870f869857441f36e269c7b7aedd6e051aaad6edc7736a71e2' 
  AND token = 'fkcDCAJEZOcO52zUBk67EYlfK200KnqATSlXvQX802w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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