SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'defc7b3519efa387fe01de3c019176ee4425891afeaff768d8129f9c46506e29' 
  AND token = 'MXfhoTGnFs0RZuOFNzBsiH9M56uoeMrnNpbZbwYKEmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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