SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4243a911b77011d915426eb087367bbf8991b3c8d5e6afd68c8044486f6407be' 
  AND token = 'hbV6Cgy+vClmyBkxQIwEoCaUoUMbwxhmB0IF3BOmlPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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