SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '211d4a8ae1b37d412b97575f9fc511cc56683537c6f822da68323345f7d6de32' 
  AND token = 'S0sHJa7QiBoewEWFRNEay3ym8qLxkMY2+lqRvMIIQbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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