SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f4cc8230d752d91dfa41d8aa91e140d4799a057ce43a6ac237b4d1a840d3d52' 
  AND token = '4nCKPnSmBUraiZ5/vbDK90NU/XRCcbh38RZYFDtRrpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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