SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '754e51abc861d6a51bfc13912f386e5a9835e82962a1e9febedb3b4124d47971' 
  AND token = 'z4tQ3JbMwqmSq/ynp62WskfqJxArgPta4YZovKiSBDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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