SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '871ed184031a888f1623fbc8975de4fa8eefeda62eefdddacef6dbf2053d14c3' 
  AND token = '2m/3b0LkiEPekowkAGIhFUAggpridz43J3B6O+HdpAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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