SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9758996128928537f8ace42f28e1d26813395b279b03565c2baa4fdff96802c3' 
  AND token = 'JdrQHBeS671I/0dE2YSK0RV/WmvfPZcDXVtYLMqeygY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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