SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e975f85732348187b0e4dfc16513518c1a5043a834af7c22d05030859c9dab46' 
  AND token = 'LKre8mT7TcpwgeYhdgU6V/tSB1U8HIeDIFFlekyFVOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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