SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '189f0e6dfedeefc9866db6e2ad326b5c15f0fd774ac9cd75b1a891ce4890c8cb' 
  AND token = 'jf7gHxmhPQqo+Tf6OpKCztGVQXk0xzcR/oZZ+Hq5k2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

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