SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c3af30d76c782db04d87b2baa72731df5cbf6b251a1b1f8b859f1142b4a1df2' 
  AND token = 'FhP7zW3u8MUhDVs9YCRCypdoYsrITh1QqaAc3wRtbCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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