SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f7b49446cc2d1334e818322631e7c9e76e05f851a9b825f307a8717fd849b4a' 
  AND token = 'pKwHzxGk9nZYLgbkIpA4vDMJRTql0z+cbU2bJUKB6TI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}