SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd40e11cd55a37cadf955fbb749e559cdb98f52bda4ff7577befbcb4991cba4d' 
  AND token = 'ADSRbky1sav6mTOtC+NpJqJbCsGTPBuqnxH1Y8Vx8Y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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