SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c93f48d252dbd8288d7404c26c13b67e14e9d23161f28be887d49f45514560a2' 
  AND token = 'ieD2QzPIX34mzBsIzlIOC+Sb4iH4szy/CUXKzPu5ewU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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