SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbbe52731f18ff23e6f0ee6be68d769ff4efb214d3dc835597ddbd8a90051cae' 
  AND token = 'Fzn0jK63aDFj+ePZRObR7/Gg+qCO+dGGt4pmCbY/Yvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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