SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd29ade0436cdcc5bd980b0dffa0da7d84ae0d6035602abd8c5a236ba1649ad4b' 
  AND token = 'SlC2cEDOk5GwTJIHE+wAM9eoka/DpaZxfyJN24JlT8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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