SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2cb1d625d018e4705ef0ce4b17f16659173491c32a73901553059224fec1992' 
  AND token = 'kE8/j+KB1CYnsHdXD/BDLOUptT/Q6pVObvi1oUmSAoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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