SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5837ab1923bb4d705db08c837ca1b09127a67a0f84d6a5627b00fa23bc4409c' 
  AND token = '7gVuEZ+Lsq5PtTlZV9W/VduEGBw24wOI7Pz/jQYb7mI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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