SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3baea22708099ff8f8389d09feb70c4cd934f0c1b3ee245d3617bc4215010648' 
  AND token = 'O3VZIzpFvjAXd514n9ePqRPNLoIS/wQKUNNmUJfiIBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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