SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ac703aad11618ee11872e155d0c24fa76583423bb3e6909fb4da825ebc49656' 
  AND token = 'izXZlpkANoVvh7VIfjRA1YZLTaXei+onNlNe3TCFIRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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