SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b18a022446cfb555499a21c79aebd35d349d1dea8de976fe0256d10938a037b4' 
  AND token = 'JdA6SPWkQY+pyVLJG+HPXVX2FfYyZNoOuFgLoHKLits=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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