SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad2a64404ed8b61d72d4f55fb5a875e7bc47de8837031cc4588991cfeded36a4' 
  AND token = 'vsV8HXKsJwgO7GVWJIAtnrUP+Nt7gyEMnv1wYQI9LRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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