SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5f683f97bedc4a7ebca030c10a2602502cb0f3810791425eb820f2bf029a0cf' 
  AND token = 'mJJtLl8GYHTXsCyCfvNQG1LpoNEwH/sZ2GWAAWPvZ3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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