SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f21731b96839e0ff0d84a9c29f737146e84eb2e2b503da382f164228540facc2' 
  AND token = 'VzhORMLjs+sUAApkr2gbVbjmEkBOZCiEC8n1bF5E6b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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