SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42e4672e98f0c8b0cf114a1fcf5f72de066fc0177ba569e9c34006b5141caa8' 
  AND token = 'KLm1mfOCcwiOSXc8girSNIQuQ5uFfK/a1HMBkuC0S0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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