SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5eff2726f6abf92c80bd50fa069bddcc24baccf2d0d90d072c85d1c0b7563bbc' 
  AND token = 'R5eGA5OkLluAOHBYSjTj584xRsxXdoufQjiAZSpYZyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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