SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f47d14b2cd4b99f810f9d479e6f721d4ae5bb46db86339b40875bd017017c2c3' 
  AND token = 'rsD9LYlX0RELWfIJfxSuf6h0o4oTHyx0wcXGP0T4fWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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