SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f4374147bd1b168dc9ec13f924b4cf7ffc69ec57d6f1b76ce1ef546632fb51' 
  AND token = 'SpJKsr5a3dGpMsupH38PWan3MGeHJZwpWuyKaaExFvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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