SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfe9c1539dd8508e955e353c31faf663ad94041f3758b5f64476799024340023' 
  AND token = 'OyJtbaFAFGQL1CZ/2E2uw38drcVQIsnNSfSEwNDXFtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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