SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8520d0ed5b55286d50347faaf962eb1c07961cb574beedd46a7726715f5a110' 
  AND token = 'DOenR4p03NMF1lKzwfi1N9ADrW8OFWcJS8xBAcd8CEk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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