SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ab68d9ab9d8406e174905e9a3fea526d9d618aa08b5f1e971f7afd13b59b271' 
  AND token = 'OTFxEFa7vjIOBXqXKl+ejZ2JXYPPsmgbPlwLjzYx2/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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