SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7fb8576025a37b0d9eebc5af0f9af139b46fcb6072e8bd655d56b4c72c80715' 
  AND token = 'DeQ/NiMPBV+nvvCDkpOPrDnVVlKU9gxHopEgVVzToeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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