SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89ceecf24408bc8005f1538fb621353bf15eb00687b4423a4d63affb06bdebb2' 
  AND token = 'kBieT/dWQ8Vt0a2UzUs0D1xCLuSl7iy3uCRfMJI6NgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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