SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cea261c69cbdd90f56b6d46554bd1395d78ea653b8b31ca15baea42ddc284c9' 
  AND token = 'Mim1IBhSLH5Otop34fzaKk2CmAwvGVCEOlgEYvH/dzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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