SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba3fbe5833d0ec968b2f73c7a537cbc586a3816124310275b59975998616f64b' 
  AND token = 'ht5gTfSidPLgNslxssCiWKwpF9eN/i/nV0rsZTLO6LY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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