SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93da6deeee35a7716802c491417856f2d7254e9d71571a16abb4c410c115eed0' 
  AND token = '0i+7GXQE4U+kFMWC9OM+djvA/rnPZ+XpSUjrhRF5avQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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