SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968e37b8ead5e86d84622f54552611de9906a0998f9a6b30541ac65c6b8b0c52' 
  AND token = 'UbToHZlDQIpsLMo6xvCbJg7DfXrnMbkdYAbyc5saJ5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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