SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf63863cb4e1fc4c43a3cdd68caa307537d7bd0899fb934f843a3479d8f230ed' 
  AND token = 'b50mrVguE7qJ/1eKaI6FjZyDeuEOmphc1K9w/+AzNgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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