SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1bbcdcc62d972d564929be14e264a9a8da1ce0a44dc988d329a94f3cb298742f' 
  AND token = 'UVR50+qSvlfQMRYzsmRoldJJmvHhtmuSg9faKMIzgNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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